Trump shooter Thomas Crooks seen at rally an HOUR before shooting in shocking new video

Donald Trump's would-be assassin Thomas Crooks was captured in a chilling video lurking near the former president's rally stage just an hour before he opened fire. 

The disturbing footage, shot by a member of the crowd, appears to show the 20-year-old gunman walking near a building he would climb 60 minutes later to unleash a hail of bullets. 

In the harrowing clip, obtained  by WTAE, the shooter does not appear to be holding the AR-style rifle he used to shoot Trump through the ear at the rally in Butler, Pennsylvania on Saturday.

The cameraman said he had been trying to capture the huge crowd waiting to watch the Republican nominee speak, but later realized he had caught a more terrifying detail in the background.

The footage was revealed amid a series of stunning developments that raise more questions about the massive security failure that led to the attempt on Trump's life.  

It emerged the gunman's' father called police on the day of the shooting because Crooks didn't return from what he thought was a Saturday trip to the local gun range. 

And it was revealed Crooks was at the former president's rally three hours before opening fire, sparking the suspicions of the Secret Service because he was carrying a rangefinder used by hunters to take long shots.

He later climbed onto the roof of the building he was lurking near, shot Trump and killed retired volunteer fire chief Corey Comperatore.

On the day of the attack Crooks had told his boss he needed the day off from work on Saturday and gave colleagues a final chilling message: That he would be back on Sunday.

His father told law enforcement he assumed his son had gone to the shooting range at the The Clairton Sportsmen's Club to practice with his rifle and would be back by 1pm on Saturday, CNN reported.

But as time went on he grew more concerned and phoned local law enforcement. 

At around 3pm on Saturday, Crooks was spotted at the rally's security screening area and tried to pass through metal detectors with the rangefinder, which is used by shooters to measure distance.

The device, which looks like a small pair of binoculars, would not have prevented him getting into the rally but did put him on law enforcement's radar. 

The Secret Service watched him but lost track of Crooks when he left the secure area.

He is then believed to have collected the rifle from his car, which also contained a bulletproof vest and two explosive devices.

Then, about 40 minutes before the shooting, Crooks was back on the Secret Service radar.

A photograph showing the sniper appearing to crawl on the ground while scouring the area was circulated to law enforcement as a suspicious sighting at 5:30pm. 

Around 6:11pm, Crooks took up a position on a slanted roof and shot at Trump, wounding him.

Witnesses reported having seen Crooks crawling onto the roof of the American Glass Research building.

A Secret Service counter-sniper team codenamed 'Hawkeye' also spotted him looking at their position through the rangefinder.  

The Clairton Sportsmen's Club where Crooks' father believed him to be heading around 1 pm states on its web site that its high-power rifle range 'has 10 firing benches with targets at 50, 100 and 187 yards.' 

Crooks is believed to have been firing from about 165 yards when his bullet struck Trump in the right ear after the former president turned to read from a stats screen.

The latest bombshell developments raised more questions about the massive security failures that led to the attempted assassination of the former president.

When approached by DailyMail.com earlier this week, club president Bill Sellitto, 77, was clearly emotional and deeply distressed at his establishment’s association with an act that he described as ‘appalling'.

‘This isn’t us,' he said. 'We are a community. We are having a youth day very soon, more than 100 kids. Members of five different police forces train with us, we support them, and they are part of our community.’

Law enforcement took a photo of Crooks an hour before the shooting, adding to mounting evidence that they knew of his presence well before he pulled the trigger.

Two more newly released images also show a bicycle owned by Crooks that was recovered close to the scene, and a remote detonator, which was recovered from his dead body alongside his cellphone. 

It was later revealed that the detonator was connected to explosives found in his car. 

The gunman was also acting strangely around the metal detectors that attendees were forced to walk through before entering the event grounds. Witnesses said that Crooks was furiously checking his phone and operating a hunting range finder.

He attempted entry around this point but set the detector off and was refused, sources said. 

Around 5:30pm a picture of Crooks was circulated to various members of the Secret Service after reports about his suspicious behavior were made to security. 

The picture shows Crooks wearing a t-shirt with the logo for popular YouTube channel Demolition Ranch.

At some point, officers lost track of Crooks. He was next seen climbing to the roof of the American Glass Research building. Around seven minutes later, he opened fire on Donald Trump.   

Trump took to the stage at 6:03 pm, an hour behind schedule. The gunfire rang out at the venue approximately 6:11 pm.   

In the wake of the shooting that killed one spectator, investigators were hunting for any clues about what may have drove Crooks, a resident of Bethel Park, Pennsylvania, to carry out the shocking attack. 

The FBI said they were investigating it as a potential act of domestic terrorism but the absence of a clear ideological motive by the man shot dead by the Secret Service led conspiracy theories to flourish. 

Investigators believe that he acted alone and have confirmed that there is no social media presence that would indicate that Crooks' attack was politically motivated. 

 Butler County Sheriff Michael Slupe told the AP that a local officer climbed to the roof and encountered Crooks, who saw the officer and turned toward him just before the officer dropped down to safety. 

Slupe said the officer couldn’t have wielded his own gun under the circumstances. 

The officer retreated down the ladder, and Crooks quickly took a shot toward Trump, and that’s when Secret Service snipers shot him, according to two officials who spoke to AP on condition of anonymity to discuss an ongoing investigation.

WPXI said multiple sources on Tuesday confirmed that Crooks was on the roof with a gun for fewer than seven minutes before he was confronted by a Butler Township police officer. 

Crooks used an AR-style rifle, which authorities said they believe was purchased by his father. 

The roof where Crooks lay was less than 150 meters (164 yards) from where Trump was speaking, a distance from which a decent marksman could reasonably hit a human-sized target. 

That is a distance at which U.S. Army recruits must hit a scaled human-sized silhouette to qualify with the M-16 rifle. 

Alongside the explosives in his car, investigators also recovered a bullet proof vest and hundreds of rounds of ammunition, which had been purchased, alongside a ladder, on the same day as the shooting. 

Another bulletproof vest, and third remote-controlled bomb was later discovered at the house he shared with his parents.

The latest revelation that a transmitter was also with him has raised fears that Crooks may have been planning to continue his killing spree if he had escaped from the roof with his life, and may have had an accomplice to help him.

Hours earlier Crooks had asked his boss for the day off, telling him he had 'something to do', before travelling to Saturday's rally.

The would-be assassin told colleagues at the Bethel Park Skilled Nursing and Rehabilitation Center that he would see them on Sunday.

But a Secret Service agent at the Butler rally ensured that he would be the last person Crooks saw as he locked eyes with the killer before shooting him dead, graphic video has revealed.

Video shows Crooks peering intently through the sights of his father's AR-style weapon and firing towards the rally as onlookers scream from the base of the building.

Instantly a second volley of shots is heard and Crooks is pictured lying dead on the roof as those on the ground gasp in horror.

'The Secret Service don't f*** around man,' one exclaims. 'Holy s***.'

He had clambered up building's air conditioning system and hoisted himself onto the roof where MAGA fans saw him 'bear-crawling' across the sloping surface with his rifle, and warned law enforcement of the danger.

'I'm thinking to myself 'Why is Trump still speaking, why have they not pulled him off the stage?,' one witness told the BBC. 'The next thing you know, five shots ring out.'

Crooks was a dietary aide at Bethel Park Skilled Nursing and Rehabilitation Center - where he provided food and care for post-hospital elderly and sick people.

'We are shocked and saddened to learn of his involvement as Thomas Matthew Crooks performed his job without concern and his background check was clean,' administrator Marcie Grimm said in a statement.

A colleague at the facility said Crooks never expressed political views at work and wasn't a 'radical'.

'It's hard seeing everything that's going on online because he was a really, really good person that did a really bad thing, and I just wish I knew why,' he added.

The would-be assassin was a registered Republican and 2022 high school graduate. Records show he donated on the day of the 2020 inauguration to a progressive group backing President Joe Biden.

He graduated from the Community College of Allegheny County in May with an associate degree in engineering science, according to school officials who said they were 'shocked and saddened by the horrific turn of events'.

Crooks' father Matthew was seen on Tuesday morning for the first time since the shooting as he opened the door of the family home to FBI agents.

A neighbor of Crooks' sister Katie said her brother helped her move into her nearby apartment three years ago, describing her as a 'hardworking' woman who worked as a janitor at a local high school and as a server at a restaurant.

Both of Crooks' parents are behavioral therapists and Crooks' father said he was baffled by his son's actions.

The Justice Department, the Secret Service and the FBI, are due to brief senators about the investigation on Wednesday Majority leader Chuck Schumer revealed on Tuesday night as the Secret Service faces intensive scrutiny over its handling of security at the rally.